The present invention relates to a video camera using a semiconductor memory or a disk-type memory as means for recording images and a video camera system for use thereof.
In a conventional video camera, as is described in National Technical Report, Vol. 37, No. 3, June, 1991, pp.263-272, a video tape recorder (VTR) is used as means for recording images taken by a video camera, wherein the camera and the VTR are accommodated in a single cabinet. The photographed images are recorded on a tape through the VTR accommodated in the cabinet, and long hours of image data can be recorded by periodically interchanging the VTR tape. However, in such a camera/VTR integrated camera, it is not possible in principle to provide a VTR portion having a size smaller than that of a cassette of the VTR tape, and, therefore, it has not been possible to realize a video camera capable of recording and reproducing images and having an ultra small size comparable to the size of the cassette.
Accordingly, it has been proposed to realize an ultra small video camera by compressing image data taken in by a camera and recording the data in a semiconductor memory without using a VTR, as in video cameras disclosed in Japanese Unexamined Patent Publication No. 253251/1994 and Japanese Unexamined Patent Publication No. 328966/1992. In the technology described here, a semiconductor memory is incorporated on an IC card which is attachable to and detachable from a main body of a video camera, such that a user can freely interchange semiconductor memories in the same manner as a VTR tape.
However, the IC card using a semiconductor memory is generally more expensive than a video tape and is not suitable for preserving a large amount of data generated over a long period of time. On the other hand, when dubbing is to be performed on a video tape by using a separate stationary VTR for preserving a large amount of image data, the time period required for the dubbing is equal to the time period for taking in images, which places an enormous burden on the user. Further, in this case, the image data recorded in digital form is converted back to data in analog form, which does not make good use of the digital recording.
Further, in the construction wherein the IC card is attachable and detachable, the probability of losing data due to static electricity, terminal failure, vibration or the like is enhanced, which significantly lowers its reliability. Meanwhile, in a construction wherein the attaching and detaching of the memory are not possible due to use of a semiconductor memory in the main body of the video camera, only a relatively small amount of image data representing a limited period of time may be recorded.